The invention relates to an operating device comprising a rod which is able to move translationally along an axis, with respect to a housing, about an equilibrium position. The invention finds particular, but non-exclusive, utility for a rotary encoder. More specifically, a rotary encoder is a device allowing data entry by means of the rotation of a rod about an axis. The data may be optically encoded in an electronic part of the device. The coder may also have additional means for inputting data when the rod is pulled or pushed about an equilibrium position. A translational force directed along the above-defined axis for rotation is then applied to the rod. The additional data input means may be used to validate a data item entered by the rotation of the rod.
To make this type of encoder more ergonomic, a number of equilibrium positions may be provided within the rotation of the rod, each position representing a separate data item. The equilibrium positions may be separated by a hard point. More specifically, the torque to be applied to the rod for passing from one equilibrium position to the next passes through a maximum. This allows a user operating the encoder to feel the rod passing at each equilibrium position. By contrast, provision has never been made for there to be a hard point for the force to be exerted when the user is pushing or pulling the rod of the encoder. The user is thus obliged either to observe that the data item entered by means of the translational movement of the rod is correctly entered or to apply a translational force to the rod which is very much greater than the force required to enter the data item, at the risk of damaging the encoder.